1. Field of the Invention
The present invention relates to electronic multiprocessor systems for processing digital and logical data--i.e., systems comprising a number of data-processing stations linked by a number of buses to exchange messages containing e.g., data, instructions, requests and so on. Multiprocessor systems of this kind are of use inter alia for controlling automatic telephone or visiophone exchange equipment, data-collecting and processing networks, automated installations for controlling the various phases of an industrial process and the switching of messages in voice mode or packet mode.
As a rule, each station comprises a processor and means for coupling the station with at least one bus link. Advantageously, the system is arranged not to use common elements, such as central control unit or central store or the like, so that for a slight complication of the stations, there are fewer restrictions on design and there is an appreciable reduction in the risks of total outage of the system. The interconnection bus network contains all the internal links of the system.
2. Description of the Prior Art
Multiprocessor systems of this kind which do not use a common element have already been described and general architecture schemes are proposed, for instance, in the article by George A. Anderson and E. Douglas Jensen entitled "Computer Interconnection Structures: Taxonomy, Characteristics and Examples" and published in the American Journal "Computing Surveys", Volume 7, No. 4, December 1975, pages 197 to 212.
As seen hereinafter, the known systems can be broken down into three kinds--a first kind, in which all stations are interconnected by a single bus carrying all traffic, a second kind, in which the system forms a linear chain in which stations and buses alternate, and a third kind, in which each station is connected to each of the other stations of the system by its own bus.
As a general rule, for a system having a given number of stations, system reliability and traffic speed increase with the number of buses used, but increasing the number of buses increases the complexity of the bus controllers and the overall cost of the system.